Apparatus for sampling fluids in geological formations



Feb. 17, 1959 ,M. F. B. PICARD APPARATUS FOR SAMPLING FLUIDS IN GEOLOGICAL FORMATIONS Filed 001}. 15. 1953 FIG-.1

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Iv APPARATUS .FOR SAMPLING'FLUIDSJN v v z GEOLOGICALFORMATIONS The-present invention relates to apparatus-for taking "samples offluids (liquids or' gases) thatare present in geological formations andin particular in the formations forming'the sidewalls of wells drilled intothe-earth.-

Explosively' propelled hollow projectiles have been em- "ployed heretofore for sampling the contents-of earth formations traversed'by a well. In one such apparatus, the hollow projectile comprises a cover which'is adapted to be sheared off when the forward part of theproje'ctile reaches the formation to permit the introduction offluid into acavity therein. Valve means is provided which is adapted'to' be closed after the entrance of the fluid so as to prevent escape ofthe latteriduring the raising of the projectile to the surface of '..the earth.

Apparatusof the'type described above hasnot been entirely-satisfactory. For :one thing, difiiculty has been experienced when operating in a well containing drilling mud, for example, in preventing, to'the maximum extent possible, the drilling mud from penetrating to the inte- ='rior of the cavity'in the projectileafter the cover has :been' sheared off, and'contaminating the I fluid sample obtained from the formation constituting 'theadjacent "wall'of the well. Also, it has not a'lwaysbeen possible to maintain good watertightness of the projectile after iithetaking of 'the sample and duringthe raising of the up'rojectile up to the surface of the earth.

=-An object of the invention, accordingly, is to provide new and improvedsample takingapparatus in which these 'difliculties are overcome'in-a satisfactory manner.

This and other. objects of the: invention 1' are attained by providing a forward part for the projectileywhich' surrounds the cover that is'to. besheared off, and'which 'is made of a metalthat-is relatively'malleable whilez'at the'same time having sufficient strength for the purpose. .The hardness of this. metal will preferably be chosen as a function of the hardness ofztheiformations against uwhichtthe sample taking device'will be projected. .In' the zcase of consolidatedisands or sandstones,..a suitable1rnetal in accordance with the inventionmight be aluminum, for 1 example, exclusive of alloys'such as .Duralumin; etc. In the case. of very. hardilimestone; on the otherihand' other types 'ofimetals. may be employed.

Preferably, the. forward'partofthesprojectile should have a relatively large. surface .area and .itishouldibe shaped inthe form: of alfrustum of aconexof large apex .iangle. By virtue of this construction, when the projectile is drivenv againstthe wall .-of.;th'e well,.its'forwardzpart .depresses a complementary portion of ithe walliandtfits .exactly against the resultingidepression .withoutr'eb'ounding so that it constitutes. an effective jointi formingia vent prolonging the duration of suction. 'T Further,"-While:..:it provides free communication between theinterionofi'the projectile (after shearing. of the cover) .and the wall zof the well, it is also of maximum efiectivenessin preventing the bore hole. liquid from. reaching .the orifice :of -the* projectile. The presence :of mudcakeon" the .wall -of the well in practice is aufavorable factor sincer this cake'constitutesa natural watertight-joint.

"-' (l-iquid*or"gas) of'whichasa'mple is to-be taken. Within 2,873,894 H Patented Feb. 1 7, 1 959 "The invention further contemplates that the retaining 'valve' disposed in the interior of the projectile; will operate'in response to differential "pressures such" that, as

"s'o'onas fluid penetrates to' the interior of the projectile tl'ie-v"alve closes and, as a result of the differential pressure exerted against its head, will maintain sufficient force to preventreop'eningof'the valve during: the rais- "ing of "the apparatus to the surfaceof the earth.

When only the fiuid contained in sandy formations-is tobe collected,3t0the exclusion of the-sand in such the fiuid. 7

"Other objects and characteristicsof the invention will appear during the'course of thefollowing description of a representativeembodiment, 'taken in conjunctionwith theaccompanying drawings in'which: 20

Fig. 1 is a View, partly in transverse section, through sample takingapparatusconstructed according-to the' in- -vention and disposed in the-interior of a-w'ell;

Fig. 2 isa viewinlo'ngitridinal section of oneof'the sample taking-projectiles-in'the apparatus shown in Fig. 1; and i I f Figx3-1is-a modification. of' the sample taking projectile'shown'in FigI'Z.

5 In"Fig. 1, 1 designates a well containing a" liquid such as drilling mud and traversing earth formations 2" which may be,-for example; sands containing fluid the well is' disposed'later'al sample taking apparatusfi inwhichare formed hollowed" out portions 4 constituting 5 guns by means of which* sample taking "tools '6 may be projected against the wall of the well as'the'result of "the explosion of powder charges 5. "While inFig. 1 only one sample taking tool is' shown, actually'the-'apparatus has formed therein a plurality of superposed hollowed out portions forming guns'each-containing a sample taking tool.

The sample takingtools 6 are connected tothe' body ofthe apparatus" by cables/7 such that' when the appa'ratus is raised to'thesurface ofthe eaith'the sample taking to'ols' are carri'dalong with "it' and 'al'so brought to the surface. This arrangement is well 'kn'ownper'se in" so far as concernsconventional lateral sample takin'gapparatus. *The purpose oft-he sample taking tool is to collect and retain samples'of fluid'contained in the well. Tothis "end, it comprises '(Fig; Zia hollow cylindrical bodyin :two'parts 8; and 9 screwed to, one another "inorder to facilitate manufacture and assembly. The ,body parts cooperate toform an"interior'-chamber.10 injithe body which'is. adapted to receive theRfluid drawn off from the "formation. 'The chamber 10 is normally'closedat 'its forward end by a valve. 11"comprising a cylindricalele- 'ment12 slidablvmountedpn a fixed piston 13. The

pistonfl13 is securedtoLthe body part 9 by mea-nsoif a disc '14. pierced with .holes'to permit fluid to pass therethrough. Packing means such as a packing ring 15.may be disposed between the piston 13.and the interior wall of the cylinder12 to insure watertightness. At the forward end .of

.the cylinder. 12. is formeda. crown member. 16 carrying inia groovepacking means such asa packing ring 17 adapted tobe appl ed against the forwarda-wall portion 18 of the chamber 10.

-A stopmember Z7 carriedzby thecylindricalbody part .Sserves to limit the movement of the valve 11 rearwardly.

' On. the forward extremity 19 of the body 9 is fitted a 'head;memb.er"20-which-is also cylindricalin-shape, and aa cavity, 21 is formed between the head member- 2W and the body forward extremity 19. Suitable packing-means the wall of the well.

such as a packing ring 22 assures watertightness between the body extremity 19 and the head member 20.

According to the invention, the head member 20 is made of a relatively soft metal such as pure aluminum, for example. In the front end of the head member 20 is formed an orifice 23 which is normally closed bya closure portion 24 formed integrally with the head member 20. The portion of the head member 20 surrounding the orifice'23 is relatively large and, in accordance with the invention, its forward face 25 is preferably shaped in the form of a frustum of a cone having a large apex angle.

In operation, the apparatus is lowered to the desired level in the well and the sample taking tools are projected in the known manner against the wall of the well by the'explosion of the powder charges. However, while the conventional sample taking tools are constructed so as to penetrate deeply into the wall of the well, the apparatus in accordance with the invention, by virtue of the large surface 25, penetrates only relatively slightly into the wall of the well as can be seen in Fig. 1,, the depth of penetration depending on the nature of the material. As a result of the violent shock which the tool undergoes against the wall of the well, the forward face 25 of the head member 20 is deformed so as to conform exactly to the irregularities in the formation constituting At the same time, under the influence of the exterior pressure which is exerted against the closure portion 24, the latter is sheared off, whereupon the substance (sand imbibed with fluid, for example), constituting the wall of the well rushes into the interior of the chamber 21.

By virtue of the shaping of the forward face of the head member which, as stated previously, fits exactly and is retained against the wall of the well, the bore hole liquid cannot reach the orifice 23. Hence, substantially only the substance coming from the formation itself enters the chamber 21.

The substances which have thus penetrated the chamber 21'under the influence of the strong pressure which they exert push against the cylindrical element 12 and penetrate eventually the chamber which they fill completely. Therearward movement of the cylindrical element 12, which is limited by the stop member 27, creates a vacuum in the space comprisesd between the piston 13 and the bottom of the interior of the cylindrical element 12. Hence, after the chamber 10 is filled, the cylindrical element 12 will close itself under the influence of the fluid pressure in the chamber 10.

As a result of the existence behind the piston 13 of a cavity which is at most at atmospheric pressure, the pressure of the substances contained in the cavity 10 is exerted over a much larger surface than that of the substances remaining outside of this cavity, so that the closure of the valve is effected under the action ofa considerable force. There is no longer any risk, therefore, that the cylindrical element 12 will open during the raising of the 'apparatus to the surface of the earth.

After the apparatus has been brought to the surface, it is necessary only to unscrew the parts 8 and 9 in order to collect the substances contained in the cavity 10, or to again lower the cylindrical element 12 after having taken out the piston 13.

In case it is desired not to collect the sand contained in the formations, but only fluid, this may be done, according to the invention, by placing in front of the valve 11 and resting against the disc 14, for example, filter means constituted, for example, by a wire screen 30 or I claim:

1. Apparatus for sampling the fluid content of geological formations and the lili'e, comprising a hollow tubular projectile adapted to be projected into a formation, means forming a temporary closure for one end of said projectile, a transverse partition formed in said projectile, a rear closure member for said projectile cooperating with said partition to form a fluid storage chamber, means forming an orifice in said partition, a valve seat formed on said partition around said orifice inside said storage chamber, a valve head in said chamber adapted to cooperate with said valve seat for normally closing said orifice, means forming a blind bore in said valve head having its open end facing said orifice, and piston means mounted inside said projectile in fixed relation 'thereto and snugly received in said bore for fluid tight sliding movement of said valve head thereon to open and close said orifice, said valve head being actuatable in response to fluid pressure communicating therewith through said orifice.

2. Apparatus as described in claim 1 for sampling the fluid content of geological formations and the like, in which said temporary closure is formed in a large cupshaped head member secured at said one end of said projectile and prevents communication between the interior and'exterior thereof, the surface area of said temporary closure being very small in relation to the over-all surface area of said head member, whereby said head member will not penetrate any substantial distance into the wall of a bore hole when projected thereagainst.

3. Apparatus for sampling the fluid content of geologic formations and the like, comprising a hollow tubular projectile adapted to be projected into a formation and having an orifice in the forward end wall thereof communicating with a fluid storage chamber therein, a member secured to the forward end wall of said projectile and having a portion extending axially of said orifice and terminating in a piston in said storage chamber, valve means having a bore with a bottom wall at one end in which said piston is adapted to be snugly received for relative sliding movement between said piston and valve means, the bottom of said piston normally lying adjacent one side of the bottom wall of said bore with said valve means closing said orifice and the other side of said bottom wall being exposed to the pressure in said storage chamber, stop means in said chamber limiting rearward travel of said valve means, and a cupshaped head member tightly fitted on said forward end of the projectile and cooperating with said end wall to form a fluid receiving chamber, said head member including means forming a temporary closure preventing communication between the interior and exterior of said fluid receiving chamber.

4. Apparatus for sampling the fluid content of gcologic formations and the like, comprising a hollow tubular projectile having a wall at the forward end thereof provided with an orifice therein, a rear closure member for said projectile cooperating therewith to form a fluid storage chamber therein, a perforated disc-like member secured to said wall at the forward end of said projectile and carrying a member extending axially of said orifice 'of. said valve means, a cup-shaped head member tightly fitted over the forward end of said projectile and cooperating therewith to form a fluid receiving chamber communicating with said orifice, means defining an opening portion in the front end-of said head member, and frangible closure means for said opening portion adaptedto be rendered ineflective upon impact with a formation, said head member being made of a relatively malleable metal and having a forward surface shaped in the form of a frustum of a cone of large apex angle.

5. Apparatus as defined in claim 4 in which said head member is made of aluminum.

6. Apparatus for sampling the fluid content of geologic formations and the like, comprising ahollow tubular projectile having a wall at the forward end thereof pro vided with an orifice therein, a rear closure member for said projectile'cooperating therewith to form a fluid storage chamber therein, a member secured to the forward end wall of said projectile and having an end portion extending axially of said orifice in the direction of said storage chamber, valve means inside said storage chamber normally seated on said forward end wall and closing said orifice, and piston and cylinder means connecting said valve means and said member end portion so as to permit relative motion therebetween to enable said valve means to be opened and closed, said piston and cylinder means comprising a piston, means forming a bore having a bottom wall at one end and in which said piston is snugly received for fluid-tight relative sliding movement therebetween in accordance with valve opening and valve closing movements of said valve means, the bottom of said piston cooperating with said bore to form a closed chamber adapted to decrease and increase, respectively, in volume in accordance with closing and opening movements, respectively, of said valve means.

7. Apparatus as defined in claim 6 together with filter 'means preventing solid particles from entering said References Cited in the file of this patent UNITED STATES PATENTS 2,055,506 Schlumberger Sept. 29, 1936 2,119,361 Schlumberger May 31, 1938 2,288,210 Schlumberger June 30, 1942 2,289,946 Weatherhead July 14, 1942 

